This invention relates to machines for reducing material such as refuse to smaller size.
In order to incinerate municipal refuse efficiently and with a minimum amount of polution, the refuse should first be reduced to a relatively small size. Shredding machines are used for this purpose, but the shredding machines of current manufacture possess several major disadvantages. For example, the spacing between the grate and the circle described by the hammers is very critical insofar as efficiency of operation and product size is concerned. Some machines have adjustable grates, but the adjustment mechanisms are difficult to operate. Moreover, the grates of the machines are usually pivoted at one end and raised or lowered at the opposite end. This results in substantial variances in spacing. In particular, the pivoted end moves very little, whereas the opposite end moves a considerable distance for any given adjustment.
Reversible machines are desirable from the standpoint that they need not be disassembled to take advantage of sharper cutting edges on the opposite sides of the hammers. The rotor is merely reversed to achieve this end. Whereas, unidirectional machines are usually designed such that the feed opening is offset to one side of the rotor so that the windage developed by the rotor does not significantly disrupt the incoming material, reversible machines have the feed opening centered directly over the rotor. Moreover, unidirectional machines are sometimes provided with vanes to divert the windage from the feed opening. In reversible machines vanes are not employed since a vane suitable for one direction of rotation is detrimental to the other direction. Because municipal refuse contains much light weight material such as paper, which is easily carried by windage, reversible machines have found little application in the refuse field.